The mine water inflow presented in solid mineral exploration reports is a predicted value. A predicted value can be said to have no practical value if its accuracy level and reliability are not determined. Neither the previous nor the current specifications require the determination of the accuracy level and reliability of mine water inflow, which has brought great difficulties to the drainage design for mine construction and caused significant economic losses in mine drainage. This paper proposes methods for determining the accuracy level and reliability of mine water inflow, as well as relevant measures to improve the accuracy of mine water inflow.